It can be pretty difficult to maintain concentration in BG3, even as a character with a good AC and CON modifier. I know this from experience, as I've played a light cleric gold dwarf with 19 AC, +2 CON, and Warding Flare. This can be contributed to the sheer amount of unavoidable chip damage you face, that the original concentration save wasn't balanced around. For those unaware, the 5e concentration CON save is a saving throw that a caster must make to maintain concentration on a spell, whenever they take damage while concentrating on a spell. The DC equals 10 or half the damage you take, whichever number is higher. If you take damage from multiple sources, such as an arrow and dragon's breath, you make a separate saving throw for each source of damage.
This means that whether you take 1 damage or 20 damage, you still have to roll at least a 10 after modifiers and maybe proficiency to be able to keep your spell up. This is a much bigger deal in BG3 than it is in 5e, because you have many more chances to be hit by 3 damage in BG3 than in 5e. It feels bad to lose your concentration to chip damage. It shouldn't be impossible, but it should be harder than it is.

My suggestion is that if Larian wishes to keep the multitude of unavoidable damage sources coming in, the minimum DC for the saving throw could be reduced to help casters feel better about using their concentration. For instance, if the DC equaled 8 or half the damage you take, it would help casters deal with the greater sources of chip damage, while also keeping the DC the same once you reach more than 20 damage in a hit.(I just threw 8 out there as an example. I have no idea if that's mathematically balanced.)

TLDR: Make concentration saves easier to pass against smaller damage sources. This may help balance out the increased amount of concentration saves that are made.